In a typical wireless communication system, since signals are transmitted and received between a fixed BS and a User Equipment (UE) via a direct link, a highly reliable radio link can be readily established between the BS and the UE. However, wireless network configuration is not so flexible due to the fixed positions of BSs in the wireless communication system. In addition, it is difficult to provide an efficient communication service in a wireless environment experiencing fluctuations in the number of required calls. To overcome these shortcomings, a multi-hop relay data transmission scheme can be implemented through fixed relays, mobile relays, or general UEs in the typical wireless communication system.
FIG. 1 schematically illustrates the configuration of a wireless communication network using relays.
Referring to FIG. 1, a multi-hop relay wireless communication system can reconfigure a network by rapidly coping with a communication environmental change and manage the whole wireless network more efficiently. For example, the multi-hop relay wireless communication system can extend cell coverage and increase system capacity. That is, when the channel state between a BS and a UE is poor, a multi-hop relay path is established through relays by installing the relays between the BS and the UE. Thus, a radio channel in a better channel state can be provided to the UE.
Furthermore, the multi-hop relay scheme may provide a high-speed data channel and extend cell coverage at a cell edge in a poor channel state with the BS.
In this manner, relays were introduced to eliminate propagation shadowing areas and are widely used at present in mobile communication systems. Compared to conventional relays limited to the repeater function of simply amplifying a signal and transmitting the amplified signal, more advanced relays have recently been developed.
The relay technology is a necessity for extending service coverage and increasing data throughput, while reducing BS installation cost and backhaul network maintenance cost in future-generation mobile communication systems. Along with the gradual development of the relay technology, there exists a need for supporting relays used for a conventional wireless communication system in a new wireless communication system.